Packages formed from plastic, polymeric film material have found widespread application in the market place for convenient and efficient packaging of all manner of food and non-food products. Packages of this nature typically are formed by folding and sealing a web of polymeric material to form a package body having front and rear package panels, with the package panels joined to each other at margins thereof. Depending upon the method of formation, the front and rear package panels may be joined to each other either by folded portions of the package body, or at seals (typically heat seals) joining the package panels to each other.
Non-gusseted packages of this type are sometimes referred to as “pillow packs”, and do not include either side gussets or top or bottom gussets. However, for many applications it is desirable to form a gusseted package that is, providing the package with inwardly-extended, pleat-like gussets at one or more margins of the package body. For example, side-gusseted packages include inwardly extending side gussets at opposite lateral sides of the package body, which side gussets join respect lateral edges of the front and rear package panels to each other.
For some applications, it is especially desirable to provide a bottom-gusseted package, that is, a package having an inwardly extending gusset at the bottom of the package body. By virtue of the breadth and stability provided by the bottom gusset, packages of this nature can frequently be configured to be self-standing, promoting efficient display for consumer selection.
Heretofore, bottom-gusseted packages have typically been formed by pleating a web of polymeric material in a direction parallel to the longitudinal axis of the web. Suitable ploughs and forming guides shape and configure the polymeric web as it moves longitudinally, including formation of a continuous, inwardly extending bottom gusset in the web material. Subsequently, suitable seals are formed transversely of the web to define individual package bodies, each including front and rear package panels, with each including a bottom gusset. Individual package bodies are formed by cutting the web of material at the transversely extending seals, with the contents of each package deposited therein either before or after cutting of the web into individual packages. Formation of an upper seal, at the margin of the folded polymeric web opposite the bottom gusset, closes and seals each package body. By this formation technique, the bottom gusset has a width that corresponds to and is the same as the width of the front and rear package panels.
As will be appreciated by this typical formation technique, the height or vertical dimension of each package body is approximately equal to one-half of the width of the polymeric web, less the dimension of the bottom gusset. As a consequence, the maximum height of any package being formed is essentially limited by the maximum width of the web of polymeric material which the forming equipment is capable of handling.
The present invention contemplates a method of forming a bottom-gusseted package, including the operation of a pair of cooperating heat-sealing jaws, which addresses the shortcomings in the conventional forming of bottom-gusseted package. This is achieved by forming each package with a bottom gusset positioned transversely of the longitudinal axis of the polymeric film web and each package. The bottom-gusseted packages of any selected height can be readily and efficiently formed.